/*
 * Copyright 2014 Treode, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.treode.async

private class OnceQueue [A] {

  private var v: A = null .asInstanceOf [A]

  def set (v: A): Unit = synchronized {
    require (this.v == null)
    this.v = v
    notify()
  }

  def await(): A = synchronized {
    while (v == null)
      wait()
    v
  }}
